Cab lamp



Nov. 28, 1944. w; BLANCHARD 2,364,020

CAB LAMP FiIed Dec. 14, 1942 2 Sheets-Sheet l m'vsn'ron TBILANCHARD 7 m lwzfl VG. ATTORNE S NOV. 28, 1944. I F, w, BLANCHARD I 2,364,020

CAB LAMP Filed Dec. 14, 1942 2 Sheets-Sheet 2 gkes is? 6 INVENTOR F5". BLANC HARD ATTORNEYS the light source.

provisionof a light intercepting andcontrolling Patented Nov. 28, 1944 s "UNITE o a STATES PAT I Thisinvention relatesto light projecting lamps for locomotive cabs and the object is toprovide v ling diaphragm so that light filters may be aragenerally improved lamp of the type disclosed in my prior patentNo. 1,947,377; granted Feb. 13, 1934; l

' The lamp disclosed inthe above'mentioned patcut is adapted tobe arranged in the upper rear tionof the cab and a plurality of front openings for illuminating the various indicating instru- .ments, the size and location of said frontopenconditions. l l l portion of the caband is provided with a series oflight emitting openings including a bottom opening for illuminating the floor and rear perranged over the central opening thereof so as to 'stillffurther reduce the extent to which the interior of the cab is illuminated by scattered light which would be objectionable under black-out A still further feature of the invention consists in the provision of a lamp in which the light in tercepting and controlling diaphragm is fitted with a light filter which absorbs all except the ultra-violet light rays coming fromthe light source. When such afilter is used the; hands and calibration of the indicating instruments may instrumentsinsuchmanner as to avoid excessive illumination or objectionableglare from the back head ofth locomotive boiler or from other light reflecting surfaces, outside the areas actually occupied by the. indicating instruments! Such lamps have now been used extensively and. have proven very satisfactoryin service.

One ofthe improvements contemplated by the present invention is theprovision 'of means for increasing the efiiciency of the lampby elimilight. whichis reflected {through the front opennating or substantially reducing the amount of.

ingsof-thelamp from inside wall surfacesof the Y lamp'casing located betweensaid openings and This is accomplished 1 by the diaphragm which is arranged-in front of and relatively close to the light source. This dia phragm is provided with a central opening, the

area and location of whichis such thatsubstantiallyall the light rays passing therethrough are directed toward the front cover of the lamp cas-.

ing without falling on and being reflected by the innerwall portions ofthe lamp casing which lie between the cover and the diaphragm. This diaphragm also has the effect. of reducing, the extent to which the interior of the cab is illuminated bylight' projected through the front openings ofthe lamp casing without objectionably diminishing the desired illumination of the instruments mounted on the back head of the boiler. .This reduction in illumination due to light.

reflected from portions ofthe lamp casing lying between the light source and the front openings is very desirable underordinary conditions but is particularly usefulin the case'of a locomotive constructing the light intercepting and controlillumination of the interior of the cab.

shown inFigtl, H Fig. 3 is a longitudinal sectional view taken be painted with a substancelwhich, when illuminated by ultra-violet light rays, is madeluminescent. This enables the indicating instruments any,

to be rendered visible with very little,-if

Another feature of the invention consists in the provision of a generally improved form of lampin which the front openings areprovided in a coverwhich is hinged at the top and is normally spring biased toclose against the front end of the lamp casing, suitable means being providedfor holding the cover in a raised or. open position when full illumination of the interior of the locomotive cab is desired. a

- Other features and advantages of theinventionwill be more readily apparent from the flolowing detailed description taken in connection.

with the accompanyingfdrawings; in which- ;Fig. 1 is a fragmentary sectional view of a locomotive cab equipped with a lamp constructed and arranged in accordance, with thishinvena Fig. 2 is a top plan view of the lamp assembly along the line 3--3 of Fig. 2.

Fig. 4 is a transverse sectional view taken sub stantially along theline 44 of Fig. 3.

t Fig. 5 is a front viewof the lamp showing the.

front openings through which concentrated beams of light areprojected onto the different indicating instruments. arranged on the back boiler head ofthelocomotive. Fig. 6 is a view similar to aslight modification. y t l o Fig. 7 is an end elevation of thelamp socket adjusting means shown inFigs. 2 and 4.

wReferr-ing more particularly to therdrawings Fig. but showing H designates the interior of a locomotive'cab equ1pped with the usual steam gaugesand other indicatingjinstruments appearing at [2. these instrumentsfbeing usually arranged in the front OFFICE portion of the cab and carried by the back head |3 of the locomotive boiler |4. My improved lamp is arranged in the upper rear portion of the cab and is supported from the cab roof |5 by any suitable arrangement of supporting bolts I6, the, lower ends of which are threadedly engaged with suitable portions II of the lamp casing |8.

The lamp casing shown in Figs. 1 to 5 inclusive includes side walls I9, a top wall 20, a bottom wall 2| and a rear wall 22, the front end 1 of the casin beingopen and fitted with a flanged ately in front of the incandescent bulb 26. As here shown this diaphragm comprises a recof which shaft 46 may be turned to swing the diaphragm 44 from the vertical or full line posicover 24 in which the front light emitting openings 25 are provided. The size and location of each opening 25 is carefully predetermined so that the beam of light projecting through each opening from the light source 26 is centered on and substantially confined to the area occupied by one of the indicating instruments I2, thereby preventing excessive distribution of the Projected light rays over portions of the boiler head I3 located outside the areas occupied by the instruments l2. The cover 24 is hingedly connected to the top wall 26 of the lamp casing by a hinge pin 21 about which the cover may be swung from the closed or full line position shown in Fig. 1 to theraised or open position indicated by the dotted lines in said figure. When the cover 24 is swun to the open or dotted line position shown in Fig. 1 it may be temporarily held in this position by engaging an edge portion of the cover with a spring-held cover supporting latch 28. which is fastened to the cab roof I5. As shown in Figs. 2 and 5 the cover 24 is normally biased to a closed position by. a cover closing spring 26a encircling the hinge pin 21.

The light source 26 comprises an incandescent lamp having a plug portion 29 screwed into a socket 313 which is mounted in a neck extension 3| formed integral with one of the side walls IQ of the lamp casing. The socket 30 is preferably carried by a plate 32 which is fastened to the outer end of the neck extension 3| by bolts 33 and wing nuts 34. The plate 32 is preferably provided with elongated slots 35 for the passage of the-bolts 33, this arrangement permitting the plate 32 and the lamp socket 311 to be raised and lowered when this is necessary to accurately position the filament of the incandescent lamp or light source 26. a

' Thetop and bottomwalls 20 and 2| of the lamp casing "arewpr'ovided, adjacent the rear wall 22,

- with openings 20a and 2 la. These openingscome municate with the upper and lower ends of a curved ventilating passage 3601. which is provided between the curved rear wall 22 and a similarly curved sheet metal plate 36, the ends of which are fastened to the walls 20 and 2| immediately in advance of the openings 20d and 2|a. The

'26 and the adjacent wallportions of the lamp casing 1-8.

. Alight intercepting and controlling diaphragm is arranged the, lamp casing :18 "immedition shown in Fig. 3 to the substantially hori- When the diazontal or dotted line position. phragm 44 is swung to the upright or full line position shown inFig. 3 it is releasably retained in such position by engagement with a spring latch 49 carried by the top wall 20 of the lamp casing. In this position of the diaphragm 44 the light from the bulb 26 is projected through the opening 45 so that practically none of this light falls onthe inside wall portions 'of the lamp casing which are located between the diathe diaphragm-44. In order to provide for this 4 the diaphragm may be provided with guide flanges 5| located at opposite sides of the opening 45 and with filter supporting lugs 53 located adjacent the lower edge of said opening. This enablesthe filter 50 to be engaged beneath the guide flanges 5| with its lower edge resting on;

the supporting lugs 53. The use of a blue filter is recommended in cases where the efiective illuminating'capacity of the lamp must be reduced to a very considerable degree to meet black-out conditions. It will be understood, however, that various other types of color filters may be used dependent upon the extent to which the effective illuminating capacity of the=lamp is to be reduced. -In some cases it may be desirable to provide thediaphragm 44 with a light filter which transmits only ultra-violet light rays. For example; when such a light filter is used the indicating instruments I'2 may be painted or coated with some substance which is made luminescent by ultra-violet light rays. In this case the ultraviolet light rays transmitted through the color filter associated with the diaphragm 44 will rene der the indicating instruments l2 visible with practically no illumination of the interior of the cab.

The diaphragm 44 is .hingedly mounted so that it may be swung to the dotted line position shown in'Fig. 3 to {facilitate placement and removal of the incandescent bulb .26. In this connection it willbe noted that the bulb 26 must be inserted and removed through the front end of the lamp casing It, there being sufficient room provided at the rear end-of the casing to provide fonthe manipulation of the bulb necessary to its insertion and removal from the lamp socket.

In Fig. 6 I have shown a slight modification in which the lamp'oasing comprises front and rear section-s; Av and B which are respectively" bolted:

section A between the front to the front and rear surfaces of the rear cab wall C, the latter being provided withan openmg C" for the transmission of light from the incandescent bulb 26 which is mounted in the rear lamp casing section B. In this case the diaphragm '44 i hingedly mounted in the front cover 24 and the opening C. u u

In both of the varrangements shown in Figs. 1 and 6 the lamp casing I8 is inclined so that the beams of light projected through the rtront openings 25 are directed downwardly against the indicating instruments l2 at such an angle that the reflected beams are directed downwardly toward the floor of the cab and therefore are not reflected directly into the eyes of the engineer. Having thus described my invention, whatI claim is: r i i A lamp casing provided with a front wall having openings therein, a source of light mounted in the rear portion of said casing at some disupright position.

tance from the front wall thereof, a rotatable shaft extending across the bottom wall of the i casing immediately in front of said source of light and provided with an operating handle 10- j catedexteriorly ofsaid casing, a centrally aperturedmetal place having its lowerT edge secured to 'said shaft 50 that said plate may be swung by appropriate rotation'of said shaft to an upright position in front of said source of light or to a horizontal position extending forwardly from said shaft, said plate being providedwith a central light transmitting aperture and being dimensioned so that the marginal edges thereof project laterally beyond the source of light into close proximity with the opposing walls of the casing when said plate is in its upright position and a spring catch secured to the top wall of" said casing and adapted for engagement with the upper edge of said plate to hold the latter in its "FREDERICK W. BLANCHARD. 

